What Is the Difference Between Petrified Wood & Driftwood?

Petrified Wood Formation

• Timbers that fell into ancient river systems were buried so fast and so deep that there was not enough oxygen present to decay or oxidize the wood. Mudslides or volcanic ash were the likely causes of such a rapid burial. Sediment, mostly silica, carried along by the river quickly filled the wood's pores and slowly began to replace the organic matter. Some petrified wood no longer has any organic matter present, but most is in a stage called premineralization, meaning that minerals have replaced the bulk of the wood's organic matter. Petrified rock remained on hillsides and cliff faces after the waters receded.

Driftwood Formation

• Driftwood floats on top of water systems or is found along shorelines after tree trunks or branches fall into the water. The wood iss not buried deep enough to escape the oxidation process and it is in a slow decay. Winds and the force of water wear away the bark and smooth driftwood by constantly eroding its surface.

Color

• Petrified wood is mostly quartz with some impurities such as iron, aluminum and copper. These materials give striking colors to the fossilized material as the metals, now exposed to the air, oxidize. Driftwood has lost most of its color and is typically ashen grey to bleached white.

Shape

• Petrified wood is usually found as cylindrical chunks with smooth breaks, as if they had been cut with modern chainsaws. The quartz, though hard, is brittle and cracks easily with pressure. Earth movements provided enough stress to fracture petrified wood and break off chunks of it cleanly and smoothly. Driftwood may be straight or curved and gnarly, depending on whether the piece is from the trunks, branches or the roots of a tree.

Age

• Arizona has a large deposit of petrified wood that has been dated at 211 to 218 million years old. Other large deposits are in North Dakota, Argentina and Egypt with similar age. Driftwood is not nearly as old, since the timber would have decayed completely over that staggering amount of time. Driftwood may be a decade to a century or so old depending on how large the piece, how cold the water and how powerful the erosion factors.